1. Field of the Invention
This invention relates generally to a system for integrating the sound radiating from multi-way loudspeakers. In particular, the invention relates to a radiation boundary integrator positioned over a mid-range sound source to prevent angular radiation from high frequencies from conforming to the contours of the cones or diaphragms of the mid-range frequency sound source.
2. Related Art
Loudspeakers and sound systems are designed to control the direction of the sound radiating from their sound sources. Sound radiating from a high-frequency sound source, with the absence of sidewalls or boundaries, will generally radiate in all directions and possibly wrap around the sound source. This severely limits the predictability and control of the direction of the sound radiation. If, however, boundaries or sidewalls are placed adjacent to the sound source, the sound radiation will generally conform to the angle between the boundary surfaces. Thus, one of the advantages with using boundaries is the ability to control the direction that sound radiates from the sound source.
Another design objective of loudspeakers and sound systems is the ability to integrate a number of mid-range sound sources adjacent to a number of high-frequency sound sources into one housing. One common arrangement involves the positioning of several vertically stacked high-frequency sound sources having two adjacent side walls extending outward from the high-frequency sound sources, such that the high-frequency sound sources are at the vertex of the two adjacent side walls. The two adjacent sidewalls are positioned at an angle relative to one another and have mid-range sound sources positioned flush in the sidewalls. As such, the cones of the mid-range sound sources form part of the sidewalls extending outward from the high-frequency sound sources.
One of the problems with the design of certain loudspeaker systems is that the cones of the midrange sound sources form a recess or depression in the adjacent sidewalls. Because the adjacent sidewalls serve as high-frequency wave-guides, the recesses or depressions in the sidewalls prevent uniform angular radiation of the high-frequency sound waves that pass over these depressions. The angular radiation of high frequencies conforms to the contours of the cones or diaphragms of the mid-range frequency sound sources, compromising both the frequency-directivity and the quality of the high-frequency sound energy.
Another problem with the above design is the limitation on the size of multiple midrange sound sources that may be mounted into the two adjacent sidewalls. Larger diameter sound sources are usually desirable over smaller diameter sound sources because they can generate greater acoustic power. However, the upper frequencies generated by the larger midrange sources can ‘lobe’ or narrow in radiation angle if sources are large compared to the wavelength. This narrowing in radiation angle is due to the finite propagation velocity of sound. To avoid upper mid-frequency narrowing, a limit is placed on the size of the mid-range sound sources that can limit the acoustic output power of the mid-frequency range sound sources.
Therefore, a need exists to integrate radiation from the mid-frequency and high-frequency sound sources to better control the angular radiation of high-frequency sound waves. Furthermore, a need exists to improve the acoustic power or energy that may be produced by the mid-range sound sources.